The problem is, consumers see that Dell, HP, Asus, Lenovo re rolling out computers with the latest chipsets and are marketing doing so. Apple risks losing sales because they choose not to stay current.
The past couple (few?) quarters we saw Apple lose significant marketshare, when others like Asus and Dell, increase sales. Clearly the consumers want value for their money and when you're spending 2,000 for a 15" MBP, you really don't want to buying a Haswell chipset that is several generations old.
I continually here how Apple doesn't need to be on the latest chipset, yet we see in this forum, so much emotion on Apple not upgrading, just look at how large the waiting for skylake thread is. If it didn't matter why are Apple's customers so anxious for it.
I know I'm using MR members as an example and they may not be a clear cut example of a typical consumer, but I do I think it shows that people want the latest chipset.